TOYOTA COROLLA ENGINE PROBLEM

2002 Toyota Corolla • 68,000 miles

Hi,
My car makes a soft clicking sound when I start it in the morning. The noise comes from the front. When I open the bonnet and listen I cant locate it, but when I close the bonnet I hear the noise from the front wheels. The noise disappears after driving for a few minutes after the engine has become warm.I went to my mechanic he told me to change my ETF which I did with no success. He checked the drive shaft and the wheel joints which are OK. He changed the bushes which were worn out he even sprayed the throttle with anti choke with no success. Another mechanic suggested that it might be the bearing next to the water pump.I am now confused! This problems came about after my friend borrowed my car and went for a 750km journey with bad roads. What might be the problem? Help!